Terra God

Terra God is a tower defense game in which you fight the enemy hordes using unique abilities of your towers and powerful combat spells. What makes this especially hard is that the enemy has towers of his own, and these towers give his forces various bonuses, including healing, armor increase and others.
The game offers 15 levels separated into 3 distinct zones: pleasant and friendly forests, cold and harsh mountains and the enemy territory - Demonlands. The levels will not let you get bored and will keep the tension up until the very end.
Try it out and enter the battle for the Earth!